在didReceiveRemoteNotification中播放声音,而在backgorund中,使用文本到语音功能

Question

所以我现在正在尝试的是当应用程序在后台接收远程通知(或者可能从暂停状态唤醒)时播放消息.

应用程序从暂停模式唤醒后,声音根本无法播放.

当应用程序在前台时,在didReceiveRemoteNotification:调用方法后立即播放声音.

didReceiveRemoteNotification:当应用程序从挂起模式唤醒时调用方法时,立即播放声音的适当方法是什么？

这是一些代码(语音管理器类):

-(void)textToSpeechWithMessage:(NSString*)message andLanguageCode:(NSString*)languageCode{

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *error = nil;
DLog(@"Activating audio session");
if (![audioSession setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker | AVAudioSessionCategoryOptionMixWithOthers error:&error]) {
    DLog(@"Unable to set audio session category: %@", error);
}
BOOL result = [audioSession setActive:YES error:&error];
if (!result) {
    DLog(@"Error activating audio session: %@", error);

}else{
    AVSpeechUtterance *utterance = [AVSpeechUtterance speechUtteranceWithString:message];

    [utterance setRate:0.5f];

    [utterance setVolume:0.8f];

    utterance.voice = [AVSpeechSynthesisVoice voiceWithLanguage:languageCode];

    [self.synthesizer speakUtterance:utterance];
}

}

-(void)textToSpeechWithMessage:(NSString*)message{

[self textToSpeechWithMessage:message andLanguageCode:[[NSLocale preferredLanguages] objectAtIndex:0]];

}

后来在AppDelegate:

[[MCSpeechManager sharedInstance] textToSpeechWithMessage:messageText];

我在Capabilities-> Background Modes部分启用了Audio,AirPlay和Picture in Picture选项.

编辑:

也许我应该启动后台任务并在需要时运行到期处理程序？我想这可行,但我也希望听到解决这种情况的常用方法.

使用此代码,当我在后台收到通知时,我会收到下一个错误:

激活音频会话时出错:错误域= NSOSStatusErrorDomain代码= 561015905"(null)"

代码561015905适用于:

AVAudioSessionErrorCodeCannotStartPlaying ='!pla',/*0x21706C61,561015905

它被描述为:

如果应用程序的信息属性列表不允许音频使用,或者应用程序位于后台并使用不允许背景音频的类别,则会出现此错误类型.

但我得到与其他类别(AVAudioSessionCategoryAmbient和AVAudioSessionCategorySoloAmbient)相同的错误

Answer 1

由于我无法重现您所描述的错误,请允许我提供一些指示和一些代码.

• 您是否正在构建/测试/运行最新的SDK？iOS X中的通知机制发生了重大变化
• 我必须假设调用didReceiveRemoteNotification必须响应来自所述通知的用户操作,例如点击通知消息.
• 无需设置任何后台模式,即可保存应用下载内容以响应推送通知.

如果以上所有陈述都是真的,那么现在的答案将集中在通知到达时会发生什么.

1. 设备接收通知
   
2. 用户点击消息
3. 应用程序启动
4. didReceiveRemoteNotification 被调用

在第4步,textToSpeechWithMessage按预期工作:

func application(_ application: UIApplication,
                 didReceiveRemoteNotification
                 userInfo: [AnyHashable : Any],
                 fetchCompletionHandler completionHandler:
                 @escaping (UIBackgroundFetchResult) -> Void) {
    textToSpeechWithMessage(message: "Speak up", "en-US")
}

为简单起见,我使用OneSignal来连接通知:

import OneSignal
...
_ = OneSignal.init(launchOptions: launchOptions,
                   appId: "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx")
// or
_ = OneSignal.init(launchOptions: launchOptions,
                   appId: "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx")
                   {
                       (s:String?, t:[AnyHashable : Any]?, u:Bool) in
                       self.textToSpeechWithMessage(message: "OneDignal", "en-US")
                   }

textToSpeechWithMessage大多数情况下都未被触及,完全符合Swift 3:

import AVFoundation
...
let synthesizer = AVSpeechSynthesizer()
func textToSpeechWithMessage(message:String, _ languageCode:String)
{
    let audioSession = AVAudioSession.sharedInstance()

    print("Activating audio session")
    do {
        try audioSession.setCategory(AVAudioSessionCategoryPlayAndRecord,
                                     with: [AVAudioSessionCategoryOptions.defaultToSpeaker,
                                            AVAudioSessionCategoryOptions.mixWithOthers]
        )
        try audioSession.setActive(true)

        let utterance = AVSpeechUtterance(string:message)
        utterance.rate = 0.5
        utterance.volume = 0.8
        utterance.voice = AVSpeechSynthesisVoice(language: languageCode)
        self.synthesizer.speak(utterance)

    } catch {
        print("Unable to set audio session category: %@", error);
    }
}